1. Technical Field
The present invention relates to information processing devices that use a revocation list.
2. Background Art
In a system in which a host (playback device) plays back a content stored on a memory card, the memory card and the host perform encrypted communication. In recent years, a method called Public Key Infrastructure (PKI) has been under study for use in encrypted communication between the memory card and the host.
In a PKI, both the memory card and the host have a private key and a public key certificate. The public key certificate includes a certificate ID and a public key and it is associated with the digital signature of a legitimate key authority.
The memory card and the host perform mutual authentication and share a session key using a method such as the Diffie-Hellman method for exchanging keys, which is based on the complexity of prime factorization, or the Elliptic Curve Diffie-Hellman (EC-DH) method for exchanging keys, which is based on the discrete logarithm problem on elliptic curves. The memory card and the host perform encrypted communication using a shared session key.
Private keys, which need to be kept confidential, may be leaked for reasons such as negligence by manufacturers or leakage of information by malicious attackers. In the PKI, a revocation list is used to stop encrypted communications in such cases.
The revocation list is a list of certificate IDs for devices whose private key has been leaked. By using the revocation list, encrypted communication can be stopped when it is determined that the certificate ID of the other party to communication is included in the revocation list.